What does HWA stand for?
HWA stands for Holmes-Wright A lantern
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Samples in periodicals archive:
Red/green naming errors very only made by 40 per cent of dichromate and 25 per cent of anomalous trichromats. An examination at high luminance following dark adaptation allows a small number of colour deficient people to pass (Cole and Vingrys, 1983). All colour deficient people male more mistakes with the low luminance setting in the dark. An examination at low luminance after dark adaptation is a very exacting test and some normals make mistakes either due to night myopia or because green/white discrimination is very close to the visual threshold (Birch and Rodem, 1993). In the UK armed services, both the Ishihara plates and the Holmes Wright Type A lantern.
Holmes-Wright lanterns: This lantern includes two different green, two red and a white light. Lights are shown in pairs of two, low or high brightness, either vertically or horizontally aligned. The test person is asked to name the colors.
Household Cavalry - CP4 RAC - CP 4 RA - CP 4 RE - CP 3 R Signals - CP 4 Infantry - CP 4 UKSF badged and attached ranks - CP 4 AAC Pilot - CP 2 AAC non-aircrew - CP 3 RAChD - CP 4 RLC - CP 3 RAMC - CP 4 REME - CP 4 AGC: RMP/MPS - CP 3 AGC: Other - CP 4 RAVC - CP 4 RADC - CP 4 Int Corps - CP 2 General List - CP 4 QARANC - CP 4 CAMUS - CP 4 CP 2 = perfect colour vision CP 4 = defective colour vision, ranging from severe to mild The grading between CP 3 and CP 4 is done with a 'Holmes Wright Lantern.
Lantern tests simulate coloured signal lights. They usually present pairs of red, white and green lights because these are the signal colours used at sea and in air navigation, and the subject is required to name the colours. There are a great number of different lantern tests which vary quite widely in the level of difficulty they present. The level of difficulty depends on the size of the stimulus and its intensity (see Cole and Vingrys 1982 for a review). The lanterns in current use are the Farnsworth lantern, now superseded by the Optec 900, the Holmes Wright Type A and B lantern.